Inhibitory effect of taurine on rotator cuff degeneration via mitochondrial protection

Degenerative rotator cuff tears do not heal spontaneously, necessitating surgical intervention. This makes prevention crucial, but effective prophylactic measures are currently lacking. Oxidative stress has recently been implicated as a cause of degenerative rotator cuff tears, while mitochondrial injury has been reported in the development of age-related rotator cuff degeneration. Taurine, which has antioxidant properties, has been found to be effective in the treatment of various mitochondrial abnormalities. This prompted us to investigate the inhibitory effect of taurine and some other antioxidants against rotator cuff degeneration using tenocytes.

Hydrogen peroxide (H₂O₂, 2 mM) was added to tenocytes in medium with 0.8 µM taurine (Group TAU), medium with 100 µM α-tocopherol (Group E), and medium with 150 µM ascorbic acid (Group C), then each medium was cultured for 24 h. Tenocytes supplemented with 2 mM H₂O₂ alone were similarly cultured for 24 h (Group H₂O₂). In each group, immunostaining was performed for the oxidative stress marker 8-hydroxy-2'-deoxyguanosine and advanced glycation end products (AGE), which contribute to the development of age-related rotator cuff degeneration. In addition, levels of reactive oxygen species were measured using a cell-based assay kit, and results were compared. Immunostaining was also performed for indices of apoptosis (caspase-9, cleaved caspase-3 and Bcl-2), and Western blotting was used to quantify activation of caspase-9 at an early stage in each group.

Oxidative stress and AGE levels were decreased in the E and C groups. Levels of all parameters were reduced in the TAU group.

Taurine showed preventative effects against rotator cuff degeneration. The simple method of administration and paucity of side effects make clinical application easy, and the clear potential as a novel prophylactic strategy against degenerative rotator cuff tear warrants further study.